I think its fuel cut, but why? [Archive] - DSM Forums: Mitsubishi Eclipse, Plymouth Laser, and Eagle Talon Forum: DSMtalk.com

: I think its fuel cut, but why?


AllGripNoSlip
12-28-2005, 09:06 PM
I just recently installed a 3" turbo back. After that I went home and fixed my boost leaks and all i could hear was air coming from out of the breather filter on the VC. I go out to test the car and as soon as i hit 15psi the car jerks violently. I thought i blew off an intercooler coupler. but after it was over the car ran just fine. All i have as far as mods are Injen style intake, 1g bov, 14b , lower intercooler piping and the turbo back. Also i seem to have a small pool of oil in my valve cover but when i checked the plug wells, they were bone dry, but the plug wires have some oil on them. Could this be a leaking valve cover gasket? and would this cause my car to act like it hits fuel cut?

Thanks

AWD_4g63
12-28-2005, 10:05 PM
yes sounds like fuel cut to me with the small amount of info on it you gave us. i just put on my 3" exhaust and am running into the same problem. The oil sounds like maybe your dipstick popped out durring a pull? check around on that...

Hey everyone i have 3" o2 eliminator, extreme intercooler FMIC kit with short route, 3" GM, MAF-Trans, MBC set at 13 psi now, 3" intake with just filter, plugs/wires, Greddy type-s bov, safc 2, gauges... anyways im hitting fuel cut anything around or over 15psi, and its spiking 18 psi and dropping back when i shift, i was wondering if i get some 660cc injectors and adjust my maft to 660's will i be ok to turn up boost? because im hitting fuel cut now and i cant get anymore than 13 psi and have a "full" pull but i was thinking adjusting for 660 injectors would keep me far enough away and i could fun 16/18 psi? And also its a homemade mbc so im thinking if i get the profec b spec2 it should take care of creeping problems?

Reason i asked is its an idea for the poster to get some bigger injectors...

thegreatms
12-28-2005, 10:13 PM
I don't think that is fuel cut.

"Fuel cut is more accurately described as: it feels like the car hit an invisible brick wall.
It is a single very violent jerk, where any sane person would think they just put a few extra holes in their block."

Does this sound like what is happening?

(53th time)

AllGripNoSlip
12-28-2005, 10:32 PM
then yes i believe it is fuel cut. no the dipstick sits just fine. I just dont understand.... i tightened every clamp super tight and i only hear hissing coming from the breather filter. perhaps i should reset the ecu because i think it has been running rich lately because of the boost leaks and when it actually hit 15psi when there were no boost leaks it added to much fuel because all the air was actually getting to the cylinder, make sense? Thanks alot for the imput guys


Hey everyone i have 3" o2 eliminator, extreme intercooler FMIC kit with short route, 3" GM, MAF-Trans, MBC set at 13 psi now, 3" intake with just filter, plugs/wires, Greddy type-s bov, safc 2, gauges... anyways im hitting fuel cut anything around or over 15psi, and its spiking 18 psi and dropping back when i shift, i was wondering if i get some 660cc injectors and adjust my maft to 660's will i be ok to turn up boost? because im hitting fuel cut now and i cant get anymore than 13 psi and have a "full" pull but i was thinking adjusting for 660 injectors would keep me far enough away and i could fun 16/18 psi? And also its a homemade mbc so im thinking if i get the profec b spec2 it should take care of creeping problems?


Do a boost leak test and try to figure out why you are hitting fuel cut first, try not to bandaid the problem.

AWD_4g63
12-28-2005, 10:44 PM
Do a boost leak test and try to figure out why you are hitting fuel cut first, try not to bandaid the problem.

Im not having boost leak problems just flowing too much air i belive. it dosnt even count air untill RIGHT before the TB plate anyways becasus of the "blow-throu" setup. I need bigger injectors?

AllGripNoSlip
12-28-2005, 10:55 PM
yea im a dumbass for not reading that part. I just did another run. i ran stock boost and it was fine. I hooked up the mbc ( 15psi ) it hit full boost at about 3300 rpm and about 4200 rpm it fuel cut and then after it fuel cut it it continued to still pull but i let off not long after fuel cut. blah :( ill try another boost leak test tomorrow at a buddies house and see what that does for me.

oldman
12-28-2005, 11:04 PM
yea im a dumbass for not reading that part. I just did another run. i ran stock boost and it was fine. I hooked up the mbc ( 15psi ) it hit full boost at about 3300 rpm and about 4200 rpm it fuel cut and then after it fuel cut it it continued to still pull but i let off not long after fuel cut. blah :( ill try another boost leak test tomorrow at a buddies house and see what that does for me.
I also do not think you have fuel cut, sounds more like bogging to me. Air out of the VC during a pressure test means boost is leaking into the crankcase via pcv, valve seal/guides or piston rings. You need to retest, make sure the intake is able to hold about 20psi when the leak test is complete.

thegreatms
12-29-2005, 10:11 PM
it hit full boost at about 3300 rpm and about 4200 rpm it fuel cut and then after it fuel cut it it continued to still pull but i let off not long after fuel cut.

That is an indication to me that it is not fuel cut. When I hit fuel cut (3' turbo back, creeped to 17psi on 14b) I could NOT keep pulling. The engine cuts out for like 2-3 seconds. The car had NO power. I had to coast off the highway, turn off the engine, and restart before I could drive again.

I also don't think you could get fuel cut on a 14B at 15psi at only 4200rpm. There is just not enough air flow at that rpm unless you have major boost leaks.

oldman
12-29-2005, 10:43 PM
That is an indication to me that it is not fuel cut. When I hit fuel cut (3' turbo back, creeped to 17psi on 14b)
You must have had some serious boost leaks as well. One time the hose from mbc to my old 16g ripped, I got up to 24psi be fore I hit fuel cut.

AWD_4g63
12-29-2005, 11:19 PM
:rolleyes: That is an indication to me that it is not fuel cut. When I hit fuel cut (3' turbo back, creeped to 17psi on 14b) I could NOT keep pulling. The engine cuts out for like 2-3 seconds. The car had NO power. I had to coast off the highway, turn off the engine, and restart before I could drive again.

I also don't think you could get fuel cut on a 14B at 15psi at only 4200rpm. There is just not enough air flow at that rpm unless you have major boost leaks.

fuel cut dosnt eliminate your car to drive, it runs fine agian after a split second of "fuel cut" and yes a 14b can hit fuel cut easily with a GOOD full exhaust, hardpipes, and boost controller. It dosnt take much. Im experienceing it now with my t-25 at 15-16 psi i know i dont have any boost leaks because of the FMIC kits hardpipes and silicone couplers all PROPERLY put together with t-bolt clamps that are very tight. I need some 650's

oldman
12-30-2005, 12:36 AM
:rolleyes:

fuel cut dosnt eliminate your car to drive, it runs fine agian after a split second of "fuel cut" and yes a 14b can hit fuel cut easily with a GOOD full exhaust, hardpipes, and boost controller. It dosnt take much. Im experienceing it now with my t-25 at 15-16 psi i know i dont have any boost leaks because of the FMIC kits hardpipes and silicone couplers all PROPERLY put together with t-bolt clamps that are very tight. I need some 650's
Fuel cut is triggered solely by air flow, nothing to do with your ability to deliver fuel. The reason 650cc will help delay fuel cut is because a piggy back system is reporting less than actual air count to the ecu, not because you have increased your actual fuel delivery capability. The fuel count trigger is a value pre-programed into your ecu which doesn't change when you install larger injectors. This is why it is impossible to hit PROPER fuel cut for a 14b or t25 on the stock fuel system without having some other issues such as boost leak, boost creep, run away boost, defective maf....etc.

97DSMblackGS-T
12-30-2005, 01:06 AM
Hey AllGripNoSlip, i have the same problem when i put on my 3' 02 elim turboback exhaust from RNR.i have the 14b turbo as well and whenever i go WOT and goes over 4-5xxx rpm, the car starts to jerk :confused: . however for me, the car feels like its not gaining anymore power and i hear a fluttering sound coming from my engine. is this also happenin to you; can you be a little more specific to how the car feels and soud as you go Wot as well?

- oh yea, as soon as it goes above 4-5xxx rpms, the boost goes crazy sky high, it jumps past the set level of 15psi. this also happenin?

AllGripNoSlip
12-30-2005, 01:39 AM
Im not sure what i have..... i think its a stutter, not fuel cut because today i got used to the violent jerk and grew some balls and decided to accelerate thru to see if it was a fuel cut or stutter and it was a stutter because a lil after full boost came on, the car did a violent jerk then continued to rev then about 500 rpm later it did another stutter so i just let off.

Previous to this I did another boost leak test which some interesting things happened. I pressurized the system to 20 psi. the stock 2g bov clamp is leaking ( i have a 1g bov and adapter ) and i have i leak thru my valve cover. when the intake was pressurized if i put my finger over the hole where the pcv gets routed into the intake, the air would release out of one of the screws on the valve cover near the #1 spark plug well which would explian the oil on my valve cover and some kind of boost leak. I also need to check my plugs and see if they are at the right gap as well. After these minor problems are fixed i will report back or if anything new comes up. Thanks for the support guys! :)

97DSMblackGS-T
12-30-2005, 09:14 AM
i just replaced my plug and wires with some ngk br7's which came properly gapped, around .028-.03...didnt fix the problem...

oldman
12-30-2005, 09:20 AM
- oh yea, as soon as it goes above 4-5xxx rpms, the boost goes crazy sky high, it jumps past the set level of 15psi. this also happenin?
You my friend has BOOST CREEP.

97DSMblackGS-T
12-30-2005, 11:29 PM
how then, after a few pulls after i put the exhaust on, the car ran like a champ. but only a couple days later is when the car jsut suddenly started acting like crap, i looked into the engine and found the vacuum line from the MBC to the wastegate acuator was off, after i put it back on it still acted funny and after putting on a better conditioned wastegate it still acts shoots way over 15psi immedietly. i tried just a regular vaccuum line from the intake to the wastegate and it still boost over 20psi. any thoughts?

-i just got a great deal of a evo3 16g for 300 that i just got. would this get rid of the "boost creep" as i would only set this at 10-13psi.

oldman
12-31-2005, 10:49 AM
how then, after a few pulls after i put the exhaust on, the car ran like a champ. but only a couple days later is when the car jsut suddenly started acting like crap, i looked into the engine and found the vacuum line from the MBC to the wastegate acuator was off, after i put it back on it still acted funny and after putting on a better conditioned wastegate it still acts shoots way over 15psi immedietly. i tried just a regular vaccuum line from the intake to the wastegate and it still boost over 20psi. any thoughts?

-i just got a great deal of a evo3 16g for 300 that i just got. would this get rid of the "boost creep" as i would only set this at 10-13psi.
As long as the original poster don't mind you jacking his thread, let's determine if you truly have boost creep first.

Run away boost = boost immediately shoots past the setting stright to infinity.

Boost creep = boost settles at setting for a brief momont then creeps up as rpm increases.

Which condition do you have?

AWD_4g63
12-31-2005, 12:24 PM
Boost creep = boost settles at setting for a brief momont then creeps up as rpm increases.


Boost creep is that but more or less its when you are cruising in a gear higher RPM and then you punch it it is suppost to stop at 15 psi but runs to 18 or so on the way up but settles to 15psi and stays (thats the most common type of "boost creep".

oldman
12-31-2005, 12:29 PM
Boost creep is that but more or less its when you are cruising in a gear higher RPM and then you punch it it is suppost to stop at 15 psi but runs to 18 or so on the way up but settles to 15psi and stays (thats the most common type of "boost creep".
Not at all correct, what you're are describing is "boost spike", boost shoots past setting then immediately settles back down to setting.

AllGripNoSlip
12-31-2005, 12:52 PM
As long as the original poster don't mind you jacking his thread, let's determine if you truly have boost creep first

no problem, were here to help each other right? I think i found a couple problems to my stuttering. my plug gap was at .036"-.038" re gapped them to .030-.031. and i have a huge crack in my valve cover so that when i hit boost the plug wires are getting soaked in oil and casuing misfires. But thanks to all your help guys, go ahead and jack my thread :P